Epoxy resin compositions comprising epoxy resin, curing agent, curing accelerator and other additives are used as a sealant of semiconductor devices or electrical parts such as transistor, IC, LSI, etc. Conventionally, amine compounds or imidazole compounds, etc. were used as curing agent or curing accelerator, while there were problems for the storage stability of epoxy resin compositions. Recently, in order to improve the storage stability, it has been proposed to use a clathrate complex comprising imidazole compounds or amine compounds as guest compounds and 1,1′,2,2′-tetrakis(4-hydroxyphenyl)ethane as host, as curing accelerator (see patent document 1). However, when 1,1′,2,2′-tetrakis(4-hydroxyphenyl)ethane includes imidazole compounds or amine compounds, the storage stability of sealant at normal temperature can be improved compared with when these compounds are used alone or in combination, while it was not sufficient to satisfy the sealant composition with respect to fine specs of semiconductors which has progressed significantly in recent years.    Patent document 1: Japanese Laid-Open Patent Application No. 2004-307545